The invention relates to an apparatus provided in a spinning preparation machine, such as a carding machine, a cleaner, or the like, for measuring distances between a sensor and clothing surfaces, where a clothed roll (main carding cylinder) cooperates with clothed flat bars which glide on slide guides by means of flat bar slide elements.
The distances between the clothing of the main carding cylinder and clothings which face same are of substantial significance as concerns machine and fiber technology. The carding result, that is, the cleaning, nep formation and fiber shortening, is to a large measure dependent from the carding clearance, that is, from the distance between the clothing of the main carding cylinder and the clothings of the traveling flats. The guidance of air about the main carding cylinder and the removal of heat are also dependent from the distance between the clothing of the main carding cylinder and the clothed flat bars. The distances are affected by various, partly opposed influences. The wear of facing clothing leads to an increase of the carding clearance which involves an increase of the nep number and a decrease of the fiber shortening. An increase of the rpm of the main carding cylinder, for example, for intensifying the cleaning effect, causes, by virtue of centrifugal forces, an expansion of the main carding cylinder, including its clothing, and thus results in a decrease of the carding clearance. A temperature increase when processing large fiber quantities and certain fiber types, such as chemical fibers, also causes the main carding cylinder to expand, so that for this reason too, the distances decrease. The carding clearance is affected particularly by the machine settings, on the one hand, and by the condition of the clothing, on the other hand. The most important carding clearance of the traveling flats type carding machine is located in the principal carding zone, that is, between the main carding cylinder and the traveling flats assembly. In most cases both clothings which border the working distance are in motion.
In practice, the quality of the flat bar clothing is regularly optically examined by an attendant. A wear results in an increase of the carding clearance. In a known apparatus described in German Patent Document DE-OS 199 23 419, the distance between a sensor and the points of the flat bar clothing is determined. The stationary sensor is associated with the traveling flats and is facing the flat bars as they are guided along their return path.